The smaller the node, the more transistors chip makers can cram onto a standard 300mm wafer - the circular sheets of silicon on which chips are engraved and then sliced out as individual products for packaging.

Not all of chips punched from each wafer work, of course. So fine are the lines of circuitry within each chip - be it memory, Flash or microprocessor - that glitches are inevitable. Chips are tested and the duff ones destroyed. The number of working ones is called the yield, and it's the goal of every chip maker to increase their yields.

The cost of a wafer produced at a given process node is the same, so the fewer chips you need to throw away, the more you can sell. And the more chips you can etch into a wafer the better, too. This increases the likelihood of a given chip being good after its been cut out of the wafer.

New production nodes take time to 'bed in', so yields tend to be low at the start and improve over time. But once 25nm is up and running, it won't be long before the combination of greater numbers of Flash chips to start with, plus better and better yields, lead to cheaper chips - and so, in turn, cheaper SSDs.

Estimates put the price of 25nm Flash at about $0.50 (£0.32) per gigabyte - assuming all the chips are good. The price for 45nm Flash is $1.75 (£1.10) per gigabyte.

And because the Flash chips are smaller, SSD makers can cram more into the same space, upping drive storage capacities.

It takes 64 34nm chips to make a 256GB SSD. The same drive can be made with only 32 25nm chips. So you can have cheaper 256GB SSDs or opt for pricier - but not double the price - 512GB SSDs.

Intel and Micron are producing sample chips now, but hope to begin mass-production in Q2. ®